Specially-formulated fluids are used during drilling and production of hydrocarbons to fulfill different functional requirements, conduct trouble-free drilling and production operations, improve drilling efficiency and productivity of wells, and enhance the return on investment. Various types of fluids having different chemical compositions are used in such hydrocarbon drilling and production processes. For example, drilling and drill-in fluids, which are generally composed of a fluid phase, a chemical phase, and a solid phase, are used while drilling for hole cleaning, borehole stabilization, cuttings suspension during non circulation, formation damage mitigation while drilling the reservoir section, and the like. As another example, fracturing and stimulating fluids, which are typically composed of a fluid phase, a chemical phase, and a pseudo solid phase, are generally used to enhance the productivity of a field, especially a field with very low matrix permeability or a field that has incurred extensive formation damage while drilling.
Each of these fluids performs various functions during drilling and production applications. For example, during drilling operations, drilling and/or drill-in fluids are circulated through the drill string to exit through the bit nozzles at high speed to remove the cuttings, clean the bit, transport the cuttings to the surface, prevent fluid loss and particulate invasion to the reservoir, and the like. Similarly, during fracturing or stimulation operations of low permeable formations, a fracturing or stimulation fluid is pumped into the formation to improve the fluid flow characteristics of the field.
Conventional micro and/or macro particle-based fluids are commonly used in many drilling fluids because of their low manufacturing cost and availability in the market at a competitive price. For purposes of this application, “micro” particle-based fluids generally have an average particle distribution of greater than about 1 micron. Whereas, the “macro” particle-based fluids generally have an average particle distribution of equal to or greater than about 1 mm.
Although these conventional drilling fluids are effective for many applications, they have limited capability and may not be suitable for some current as well as some future drilling and production operations due to the increasingly challenging conditions of such operations. Many of the conventional micro and/or macro particle-based drilling fluids have limited functional capabilities due to size effect, have low area-to-volume ratios, are difficult to manipulate to prepare tailor-made particles with custom-made properties, predominant role of physical and gravitational forces in the particle behavior, and have a lack of quantum effect due to trivial boundary effects.
Over the years, the operational conditions of drilling and production have continued to become increasingly more extreme. For example, changes in the operational depth, nature of subsurface geohazards with increasing depth, length of horizontal departure to maximize production, complexity of drilling operations, shape of wellbore profiles or number of laterals from a mother bore to maximize reservoir contact, and the like, all make drilling and production much more difficult. Moreover, the significant changes in the physical, chemical, and thermal conditions of deeper horizons restrict the use of many conventional drilling fluids above a certain operational set point due to the limited physical, chemical, thermal, and time dependant stability of many conventional drilling fluids.
Because of the current limitations that exist using conventional drilling fluids, it is often impossible to fulfill certain functional tasks that are essential in challenging drilling and production environments using conventional macro and micro type fluid additives. A need exists for strong, stable, and customizable fluids to use in all areas of oil and gas exploration and exploitation.
Nanoparticles are becoming increasingly popular for use in developing viable drilling, drill-in, fracturing, and stimulation fluids, particularly water-based drilling fluids or muds, for example, biologically-stable drilling and completion fluids using silver nano-particles, non-corrosive drilling fluids using nano-zincoxide, thermally-stable fluids using nano-silica, high-thixotropic fluids using nano-clay. Due to totally unexpected and, in certain cases, highly enhanced chemical, mechanical, electrical, physical, thermal, and hydrodynamic properties and interaction potential of nanomaterials compared to their parent materials, nanoparticles are of interest as a material of choice for developing viable drilling, drill-in, fracturing, and stimulation fluids for oil and gas field applications. Moreover, due to the scope of manufacturing of tailor-made nanomaterials with custom-made functional behavior, ionic nature, physical shape and sizes, charge density/unit volume, nanotechnology is being used in the development of new drilling, drill-in, fracturing, and stimulation fluids for drilling, production, and stimulation-related applications.
Unfortunately, the formulation of viable drilling, drill-in, fracturing, and stimulation fluids has been difficult using nanoparticles due to the active role of surface and molecular forces in the nanomaterial behavior. The solution to this problem in other industries has been to use a chemical dispersing agent, solvents, surfactants, and/or various other additives to prepare a viable nanofluid with homogeneous characteristics and long-term stability. Because the oil and gas industry uses huge quantity fluids to drill a well, the high cost of using expensive additives, such as chemical dispersing agents, in the preparation of nanofluids is not feasible for oil and gas field applications.
Drilling fluids contribute to some of the biggest drilling and production costs associated with hydrocarbon recovery. Minimization of the cost factor associated with fluids, especially nano-based fluids, is one of the major considerations in nanofluid formulation and preparation. Moreover, nanomaterials are also very costly on their own. The addition of another costly chemical as a dispersing agent could increase the cost of nano-based drilling fluids far beyond the industry acceptable economic norm. The industry needs a technically reliable and economically attractive method for the preparation of a stable nano-based drilling fluid to meet the current as well as future technical needs and challenges of the oil and gas industry.
Besides cost, other factors, such as the environmental impact of such drilling fluids, come into play when developing drilling fluids. Due to the enactment of increasingly strict environmental laws and regulations and setting of high environmental norms by environmental protection agencies, and federal, state and local governments, environmental factors are another major consideration in oil and gas field applications due to the requirement for huge volumes of nanofluids compared to other industries. The oil and gas industry needs an economically attractive and environmentally friendly fluid additive to prepare water-based nanofluids with a view to maintain the environmental friendliness of the fluid. For example, it would be desirable to have an improved process for refining naphtha that resulted in an improved gasoline blend.
Typical micro and nanoparticle-based mud formulations using aqueous and non-aqueous fluids require different types of mud additives to fulfill various functional tasks while drilling. This is due to the fact that conventional mud additives that are used in drilling, drill-in and completion fluid formulations are single functional. In other words, they are able to perform a single task in the fluid system. The use of single functional additives in the fluid system increases the total number of mud additives and increases the total concentration of the particles in the fluid systems. This high particle concentration of the fluid system has a detrimental effect on the rate of penetration, due to the fact that mud performance (i.e., penetration) is inversely proportional with particle concentration in the drilling mud. Additionally, costs are directly proportional with particle concentration, contributing to higher costs associated with conventional methods and mud additives.
It would be advantageous to have a mud formulation with a reduced amount of additives, and therefore, a lower overall cost. It would also be advantageous to have a mud formulation having better dispersion of the particles and increased rates of penetration and overall performance of the drilling mud. It would also be advantageous to have a mud formulation that reduces handling, transportation, storage, and mud management costs associated therewith, contributing to additional reductions in the total drilling cost.
It would be advantageous to have a multifunctional mud additive for a conventional and nano-based fluid formulation that has similar or better technical performance and environmental compliance compared to conventional eco-friendly mud systems.
It would also be advantageous to have a multifunctional mud additive that provides effective shielding to the nanoparticles or nanoflocs to minimize the effect of molecular, Wan der Waals, and other surface forces.
It would be advantageous to have a multi-functional mud additive that maintains the short and long term stability of nano-based fluids by steric stabilization of the nanoparticles to prevent their flocculation, aggregation, bundling and precipitation.
It would be advantageous to have a multifunctional mud additive that serves as a secondary viscosifer to create a synergistic effect on the viscous properties of the nano-based fluid. It would also be advantageous to have a multifunctional mud additive that enhances the gelling properties of the nano-based fluid during the period of non-circulation. It would be advantageous to have a multifunctional mud additive that controls American Petroleum Institute fluid (API) loss below an API recommended value.
Furthermore, it would be advantageous to have a multifunctional mud additive that produces a well-dispersed, very thin, low permeable mudcake on a borehole wall. It would also be advantageous to have a multifunctional mud additive that has no detrimental effect to the surrounding environment, ecosystems, habitats, and the like. It would be advantageous to have a multifunctional mud additive that has no detrimental effect on the health and safety of mud technicians, mud engineers, and the rig crews. Furthermore, it would be advantageous to have a multifunctional mud additive that reduces the total number of mud additives required for the formulation of macro and nanoparticle based fluids. It would be advantageous to have a multifunctional mud additive that provides an economically attractive mud formulation for oil and gas industry applications.